Changes in the Chemical, Technological, and Microbiological Properties of Kefir-Fermented Soymilk after Supplementation with Inulin and Acrocomia aculeata Pulp

Abstract

Soymilk has received a lot of attention due to its nutritional value, especially its high protein and isoflavone contents. The objective of this study was to develop a beverage fermented with kefir biomass from soymilk supplemented with 3.5 or 7.0% of Acromia aculeata (Jacq.) Lodd. powder-pulp (also known as the bocaiúva or macaúba) (BO3.5 or BO7.0, respectively), 3.5% of inulin (IN3.5), or 3.5% of each ingredient (BO + IN). The beverage was produced from soymilk (9 °Brix) by fermentation with kefir (4 g:100 mL) for 12 h at 25 °C. The characteristics of the beverages (pH, titratable acidity, soluble solids, color, syneresis, sedimentation, and the microbiological counts of Lactococcus, Lactobacillus, and yeasts) were evaluated during 16 days of storage (0, 6, 11, and 16 days) at 7 °C. The addition of bocaiúva powder-pulp and/or inulin did not change the pH value of the beverage, which remained the same at a safe level throughout storage (pH < 4.5); it increased the soluble solids, especially when compared to supplementation of the studied ingredients (BO3.5, BO7.0, and IN3.5); and decreased syneresis when increasing the supplementation (CONT to other treatments), regardless of treatment. Kefir-fermented soymilk was classified as hypotonic (<270 mOsmol/kg) before supplementation and isotonic (270–330 mOsmol/kg) after supplementation with inulin and/or bocaiúva powder-pulp (or both). Evaluation of the microbial populations in the fermented beverages showed that this substrate could maintain viability above 107 CFU/mL throughout the storage period. The supplementation improved the technological characteristics of kefir-fermented soymilk without altering the viability of the beneficial microorganisms present in kefir.